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Fix array overruns in the new Filling solver pass.

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Probably because I wrote a couple of loops up to the maximum cell
value using the non-idiomatic <= for their termination test, I also
managed to use <= inappropriately for iterating over every cell of the
grid, leading to a couple of references just off the end of arrays.

Amusingly, it was the Emscripten front end which pointed this out to
me by actually crashing as a result! Though valgrind found it just
fine too, once I thought to run that. But it comes to something when
running your C program in Javascript detects your memory errors :-)
This commit is contained in:
Simon Tatham
2015-10-21 18:32:15 +01:00
parent 90af15b43e
commit 1cf403ceb8
1 changed files with 2 additions and 2 deletions
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4
filling.c
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@ -977,7 +977,7 @@ static int learn_bitmap_deductions(struct solver_state *s, int w, int h)
* reached by extending an existing region - we don't need to * reached by extending an existing region - we don't need to
* know exactly _how far_ out of reach it is. * know exactly _how far_ out of reach it is.
*/ */
for (i = 0; i <= sz; i++) { for (i = 0; i < sz; i++) {
if (s->board[i] == n) { if (s->board[i] == n) {
/* Square is part of an existing CC. */ /* Square is part of an existing CC. */
minsize[i] = dsf_size(s->dsf, i); minsize[i] = dsf_size(s->dsf, i);
@ -1024,7 +1024,7 @@ static int learn_bitmap_deductions(struct solver_state *s, int w, int h)
* in the bitmap reinstated, because we've found that it's * in the bitmap reinstated, because we've found that it's
* potentially reachable by extending an existing CC. * potentially reachable by extending an existing CC.
*/ */
for (i = 0; i <= sz; i++) for (i = 0; i < sz; i++)
if (minsize[i] <= n) if (minsize[i] <= n)
bm[i] |= 1<<n; bm[i] |= 1<<n;
} }